Straylight and long term follow-up after Descemet stripping endothelial keratoplasty (DSEK) I.J.E van der Meulen1, C.P. Nieuwendaal1, R. Lapid-Gortzak1, T.J.T.P van den Berg2 1 Department of Ophthalmology, Academic Medical Center, Meibergdreef 9, 1100 DD Amsterdam, the Netherlands 2 Netherlands Institute for Neuroscience, Netherlands Royal Academy, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands The authors have no financial interest in the subject matter of this poster

Background Forward light scatter causes straylight and disability glare which can be measured by the Oculus C-Quant, using the compensation comparison method. This is a psychophysical test, resulting in the straylight parameter s. Usually log(s) is used.

Background Log(s) shows a physiological increase with age. Disturbances to optical media, like corneal thickening in Fuchs’ endothelial dystrophy, lead to reduced quality of vision through increased straylight. The effect of DSEK on straylight values is still unclear. Normal values of log(s) adjusted for age with 95% confidence intervals 0.3 log(s) increase = 2x increase in straylight 1.0 log(s) increase = 10x increase in straylight

Purpose To report long term (6 months to 5 years) postoperative outcomes of DSEK. To correlate the clinical characteristics of the cornea with quality of vision as evaluated by best corrected distance visual acuity (BCDA) and straylight values.

Methods 34 eyes of 26 patients were included which had undergone DSEK between March 2003 – May 2008 for Fuchs’ endothelial dystrophy. In a previous study performed in July 2006 some of the same eyes were measured. (Nieuwendaal et al., Cornea, 2009) Data from this study (BCDA, corneal pachymetry and endothelial cell density) were used for comparison with the present study.

Methods Examinations: Best corrected distance visual acuity (BCDA) Straylight measurements using the Oculus C-Quant Semi-quantitative slitlamp grading of interface and stromal changes (0 = normal, 5 = diffusely dense corneal opacification with corneal edema and descemet folds) Corneal pachymetry of total cornea, recipient cornea and donor disc with anterior segment OCT ( Visante AS-OCT) Endothelial cell density (ECD) using Topcon Subjective complaints were documented with the NEI-VFQ-39 questionnaire and a straylight questionnaire

Results Parameter Present Average (±SD) Median (range) Number (n) Past Age (years) 72.1 ±11 72 (48 – 91) 26 patients 67.7 ±12 69.3 (45-82) 15 patients Visual acuity (logMAR) 0.33 ±0.19 0.34 (0 – 0.72) 33 eyes 0.27 ± 0.18 0.2 (0 – 0.8) 32 eyes Straylight (log(s)) 1.47 ± 0.19 1.49 (1.07 – 1.78) 34 eyes n.a. Postoperative time (days) 1027 ± 453 936 (189 – 1921) 548 ± 311 561 (90 – 1046) 19 eyes Endothelial cell density (cell/mm2) 994 ± 507 821 (535 – 2813) 31 eyes 1478 ± 378 1508 (909 – 2400) 18 eyes Interface grade (0-5) 0.85 ± 1.08 1 (0 – 4) Stromal grade 0.18 ± 0.46 (0-2) Endothelial grade (0-5) 0.50 ± 0.56 Total cornea grade 1.53 ± 1.27 asOCT total at centre (μm) 609 ± 56 614 (494-722) 26 eyes 548 ± 43 533 (470 – 627) 14 eyes

Results 2 Straylight versus age: The central red line represents average straylight values of healthy pseudophakic eyes, which show a steady increase with increasing age. The two black lines represent ± 0.2 log intervals. Straylight values in DSEK patients show a statistically significant (p < 0.001) average difference of 0.12 log units compared to straylight values of normal pseudophakic patients. Present BCDA versus past BCDA: BCDA results hardly changed with longer-term follow up after DSEK.

Results 3 BCDA versus straylight: Straylight values showed a statistical relationship with BCDA, although the relationship is not very strong (n = 33, r = 0.456, p = 0.008). Preoperative (given at the vertical axis, at x = 0), earlier postoperative and present postoperative ECD versus postoperative time: striking intra-operative and early postoperative cell loss. After 6 months stabilisation to an average of 14% endothelial cell loss per year (red line). Mean postoperative EC loss correlated with recipient ( P< 0.03) and donor age (P< 0.02)

Results 4 Also no statistical relation was found between ECD values and BCDA. BCDA correlated with total grade of corneal haze (r = 0.50, P < 0.01), whereas straylight did not (r = 0.27, P = 0.12). Mean score on the NEI-VFQ-39 questionnaire was 77/100 and mean score on the straylight questionnaire was 46/100, indicating mild to moderate visual impairment compared to normal subjects, mostly due to straylight. The NEI VFQ 39 questionnaire weakly correlated with BCDA, but not with other parameters, as did the straylight questionnaire. Corneal thickness measurements by asOCT (anterior segment optical coherence tomography) versus ECD: The lines connect points of the same patient. There exists no relation between ECD values and corneal thickness.

Discussion and conclusions Straylight after DSEK remains elevated compared to age-normal (pseudophakic) eyes. BCDA remains worse compared to normal eyes. No significant change in BCDA is found between 6 months and 5 years postoperatively after DSEK. Reduced quality of vision after DSEK might be caused by changes in the host cornea (e.g., subepithelial fibrosis) or by the graft-host interface, which probably increases forward light scatter. 1,2,3 1) Patel SV. Ophthalmology 2007;114:627-8. 2) Patel SV, McLaren JW, Hodge DO, Baratz KH. Am J Ophthalmol 2008;145:97-105. 3) Patel SV, Baratz KH, Hodge DO, et al. Arch Ophthalmol 2009;127:153-60.

Discussion and conclusions Few studies discuss long-term endothelial cell loss after DSEK. 4,5 In our population, ECD shows a significant decrease postoperatively, without any changes in corneal thickness or quality of vision as yet. If the ECD loss continues in this rate of 14% cell loss/year, in 4-5 years the average ECD will reach 500 cells/mm2. Problems with decreased quality of vision must be anticipated in future. 4) van Dooren BT, Mulder PG, Nieuwendaal CP, et al. Am J Ophthalmol 2007;144:471-3. 5) Lee WB, Jacobs DS, Musch DC, et al. Ophthalmology 2009;116:1818-30.